<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title></title>
		<style type="text/css">
			/*先清除默认样式,加字体*/
			
			* {
				padding: 0;
				margin: 0;
				font-family: "微软雅黑";
				font-size: 16px;
			}
			
			.nav {
				width: 200px;
				height: auto;
				position: fixed;
				top: 200px;
				left: 0;
				cursor: pointer;
				/*原来改变鼠标指针*/
			}
			
			.nav-1 {
				font-size: 16px;
				line-height: 50px;
				text-align: center;
				border-bottom: 1px solid red;
			}
			
			.nav-1 li {
				list-style: none;
				width: 200px;
				height: auto;
				line-height: 50px;
				display: none;
				position: relative;
				border-bottom: 1px solid chartreuse;
			}
			
			.nav-1:hover li {
				display: block;
			}
			.nav-q{
				width: 200px;
				height: auto;
				display: none;
				position: absolute;
				left: 200px;
				top: 0;
			}
			.nav-q li{
				list-style: none;
				width: 200px;
                height:50px ;				
				line-height: 50px;
			}
			.nav-1 li:hover .nav-q {
				display: block;
			}
			
		</style>
	</head>

	<body>
		<div class="nav">
			<div class="nav-1">
				首页内容慕课网
				<ul>
					
					<li>第二层
						<div class="nav-q">
							<ul>
								<li >三级</li>
								<li >三级</li>
								<li >三级</li>
							</ul>
						</div>
					</li>
					<li class="nav-1">第二层</li>
					<li class="nav-1">第二层</li>
				</ul>
			</div>

		</div>
	</body>

</html>